Collenibola 7 a 
Unguis (fig. 30) slender, curving, unidentate beyond the middle of the inner 
margin. Unguiculus exceeding the unguis, slender, gradually tapering from the 
base into a fine filament. Anal spines (fig. 31) two, feebly curving, half as long 
as hind ungues, on separated papillae, one-fourth as long as the spines. Clothing 
(fig. 32) of short curving simple setse, with long erect simple sensory setse. 
Length, 2.4 mm. 
This species belongs near the common arynatus Tullberg, and comes nearest 
to octop'unctatus Tullberg, a rarely recorded species that has never been fully 
described. If the form here described proves to agree with octopunctatus in 
Tespect to pseudocelli and the minute structure of the antennal sense organs, it 
should be regarded as a variety of that species. 
Three cotypes, from rotten driftw^ood at Bernard harbour, Northwest 
Territories, June 19, 1915. F. Johansen. 
Tetracanthella wahlgreni Axelson. 
Plate 4, figs. 33-37; plate 5, figs. 38-41. 
Tetracanthella pilosa Schott, 1894 (part), 1902 (part). — Lie-Pettersen, 1896. 
Wahlgren, 1899b, 1900b, 1906b.— Axelson, 1900. 
Tetracanthella coerulea Schaffer, 1900a, 1900b. 
Tetracanthella ivahlgreni (Axelson) Linnaniemi, 1907, 1912. Bagnall, 1914. 
Dark blue. Body elongate, narrowing posteriorly (fig. 33). Eyes on 
black patches, 8 -|- 8 (fig. 34) ; the two inner proximal eyes of each side smaller 
than the others; the three posterior eyes in a group apart from the five anterior. 
Postantennal organs (fig. 34) elongate, subelliptical, eight or nine times as long 
as broad, and four times as long as the diameter of an adjacent eye; sometimes 
constricted near the middle. Antennae shorter than the head, with segments in 
relative lengths about as 9:13:10:19. Sense organ of third antennal segment 
(fig. 35) consisting of a pair of slender curving sense rods, subtended by a thick 
chitinousridge, and covered with an integumental fold. Fourth antennal segment 
with subapical papilla and with slender curving sensory setae. Second, third, 
and fourth abdominal segments subequal in length dorsally. Genital and anal 
segments confluent, bearing two pairs of spines (figs. 36, 37). Posterior spines 
a little longer than hind ungues, feebly curving, on stout papillae almost half as 
long as the spines. Anterior spines similar to the posterior, but a little shorter, 
x'^no-genital segment with long stiff hairs projecting beyond the apex of the 
abdomen, which are simple in some specimens but apically bent and knobbed 
in others. Anus ventral. Unguis stout, untoothed (fig. 38). Unguiculus 
extending half to three-fifths as far as the unguis, lanceolate, acuminate. Clavate 
tenent hairs two, extending as far as, or farther than, the unguis. Femur with 
a single long clavate hair (fig. 33). Furcula short, appended to the fourth 
abdominal segment, and extending to the posterior margin of the third. Manu- 
brium stout, with several pairs of dorsal setae (fig. 39). Mucro and dens not 
demarkated from each other. Mucro-dentes convergent, in form as in figs. 39 
and 40; each with three setae: two dorsal and one ventral. Rami of tenaculum 
bidentate (fig. 39) ; corpus with a single stout seta. General clothing of few 
short equal curving simple setae in the middle region of each segment, with long 
outstanding simple sensory setae in a single transverse series on most of the body 
segments (fig. 41). Cuticula not tuberculate, but figured. Length, 1.8 mm. 
The term figured, as applied to the cuticula, means that the integument is 
divided into minute polygonal areas. 
Li two specimens the long distal hairs of the abdomen were simple; in one 
specimen, however, they were distinctly bent apicalh", with a minute terminal 
knob, as in my fig. 36. Linnaniemi ('12, p. 1.04), not having seen these clavate 
hairs as described by Schott, suggested that the appearance of terminal knobs 
was due to adherent particles of foreign matter. 
